Field Notes, 184 Articles

Notes from the foundry

Engineering essays on generative AI, retrieval systems, and what it takes to ship intelligent software to production.

Spin Up Sandboxed Subagents with the Antigravity CLI
gradient-mesh
Tutorial // DevTools#161

Spin Up Sandboxed Subagents with the Antigravity CLI

Google's Antigravity 2.0 CLI lets you delegate work to sandboxed subagents. A practical walkthrough of wiring it into a real dev workflow.

2026-06-19
Read Note
Build an MCP Server to Connect Claude to Your Database
midnight
Tutorial // MCP#162

Build an MCP Server to Connect Claude to Your Database

A practical tutorial on the Model Context Protocol: build a TypeScript MCP server that lets Claude query your database safely, with tools and guardrails.

2026-06-19
Read Note
Self-Host a Coding LLM with vLLM
gradient-mesh
Tutorial // Infrastructure#163

Self-Host a Coding LLM with vLLM

Open-weight coding models are good enough to self-host now. A practical guide to serving one with vLLM and calling it through an OpenAI-compatible API.

2026-06-18
Read Note
Build a Semantic Search Engine with Embeddings and Qdrant
split
Tutorial // Search#164

Build a Semantic Search Engine with Embeddings and Qdrant

A Python tutorial: embed your data, store it in Qdrant, and run semantic search that understands meaning, then add keyword hybrid search and reranking.

2026-06-18
Read Note
Shipping Generative AI Features Without Breaking Production
midnight
Engineering // LLMs#165

Shipping Generative AI Features Without Breaking Production

A field guide to taking LLM-powered features from a flashy demo to a system you can trust on a Friday afternoon.

2026-06-18
Read Note
Build an AI Voice Agent with Twilio and a Realtime Model
terminal
Tutorial // Voice AI#166

Build an AI Voice Agent with Twilio and a Realtime Model

Wire a phone number to an AI: a Node tutorial connecting Twilio Media Streams to a realtime speech model so callers can talk to your agent.

2026-06-17
Read Note
Build an OAuth-Secured MCP Server
midnight
Tutorial // MCP#167

Build an OAuth-Secured MCP Server

Secure a Model Context Protocol server with OAuth 2.1. A TypeScript walkthrough of bearer token validation, scopes, and protecting tools.

2026-06-17
Read Note
Build a Durable Multi-Step Workflow with Claude Opus 4.8
geometric
Tutorial // Workflows#168

Build a Durable Multi-Step Workflow with Claude Opus 4.8

Opus 4.8 shipped with a dynamic workflow capability. Here's how to build a crash-safe, multi-step workflow that an LLM drives end to end.

2026-06-16
Read Note
Add an Eval Harness to Your LLM App
split
Tutorial // Evals#169

Add an Eval Harness to Your LLM App

Stop shipping on vibes. A TypeScript tutorial for building a lightweight eval harness: datasets, scorers, an LLM-as-judge, and a CI gate.

2026-06-16
Read Note
Build a Code Completion Backend with Codestral
editorial
Tutorial // DevTools#170

Build a Code Completion Backend with Codestral

Codestral is Mistral's model built for code. Here's how to stand up a fill-in-the-middle code completion backend you can wire into an editor.

2026-06-15
Read Note
Build a Multi-Agent Workflow with LangGraph
prism
Tutorial // Agents#171

Build a Multi-Agent Workflow with LangGraph

A Python tutorial: model a researcher, writer, and reviewer as a LangGraph state machine, with shared state, conditional edges, and a review loop.

2026-06-15
Read Note
Build an AI Code Review Bot for Your Pull Requests
midnight
Tutorial // DevTools#172

Build an AI Code Review Bot for Your Pull Requests

A TypeScript tutorial: a GitHub Action that sends your PR diff to Claude and posts a focused, useful review comment, without the noise.

2026-06-14
Read Note
RAG Is Not a Silver Bullet · It's a Retrieval Problem
terminal
AI // Retrieval#173

RAG Is Not a Silver Bullet · It's a Retrieval Problem

Why most retrieval-augmented generation systems underperform, and the unglamorous fixes that actually move the needle.

2026-05-29
Read Note
How to Evaluate an AI Development Partner
terminal
Insights // Hiring#174

How to Evaluate an AI Development Partner

A practical checklist for CTOs vetting an AI development agency, covering evals, IP, security, cost, and the questions that separate builders from demo shops.

2026-05-22
Read Note
Vendor Lock-In with LLMs: How to Keep Providers Swappable
prism
Insights // Architecture#175

Vendor Lock-In with LLMs: How to Keep Providers Swappable

Prices change, models get deprecated, and providers face export limits overnight. How to architect LLM features so you can switch providers without a rewrite.

2026-05-15
Read Note
Cutting LLM Cost 50% Without Wrecking Quality
prism
Insights // Cost#176

Cutting LLM Cost 50% Without Wrecking Quality

A practical playbook for bringing down LLM spend: model routing, prompt caching, context discipline, and batching, with the quality tradeoffs spelled out.

2026-05-08
Read Note
What It Really Costs to Run an LLM Feature in Production
editorial
Insights // Cost#177

What It Really Costs to Run an LLM Feature in Production

Token bills are only part of it. The true cost of an LLM feature: inference, retrieval infra, evals, monitoring, and the engineering time nobody budgets for.

2026-05-01
Read Note
Should We Self-Host an LLM? A Cost and Control Framework
prism
Insights // Infrastructure#178

Should We Self-Host an LLM? A Cost and Control Framework

Self-hosting an open-weight model can save money or quietly cost more. A CTO's framework for deciding based on volume, privacy, control, and the true total cost.

2026-04-24
Read Note
RAG vs Fine-Tuning vs Long Context: Which, and When
midnight
Insights // Architecture#179

RAG vs Fine-Tuning vs Long Context: Which, and When

Three ways to get a model to use your data, often confused. When retrieval, fine-tuning, or a big context window is the right call, and when to combine them.

2026-04-17
Read Note
When AI Is the Wrong Tool (and Cheaper Options Win)
split
Insights // Strategy#180

When AI Is the Wrong Tool (and Cheaper Options Win)

Not every problem needs an LLM. A candid look at where rules, search, or plain software beat AI, and how to tell before you spend the budget.

2026-04-10
Read Note